Textured graphite sheet infused with a sealant

Abstract

A method for sealing flexible graphite sheets formed from exfoliated graphite particles is provided. A textured surface is provided onto the graphite sheet to facilitate the infusion of a sealant into the internal pores of the sheet.

1. A method for sealing a graphite sheet having opposed planar surfaces defining an interior portion therebetween, said sheet being formed from exfoliated graphite particles to provide said interior with pores, said method comprising:
 a. providing a plurality of holes extending from said interior of said sheet to at least one of said planar surfaces, wherein said holes are in fluid communication with said pores;  
 b. providing a sealant consisting essentially of a curable sealant composition in liquid form;  
 c. permitting said curable sealant composition to flow through said holes into said pores; and  
 d. curing said curable sealant composition contained within said holes and said pores, such that said holes and said pores are filled substantially with the cured sealant composition to seal said graphite sheet.  
 
     
     
       2. The method of  claim 1  further comprising a tool having a plurality of protuberances for providing said holes by pressing said tool onto said one planar surface. 
     
     
       3. The method of  claim 1  wherein selecting said sealant includes selecting a sealant from the group consisting of a phenolic resin, a vinyl resin, a silicone resin, an acrylic resin, an epoxy resin, and combinations thereof. 
     
     
       4. The method of  claim 1  further including the step of providing a free radical initiator to initiate cure of said sealant. 
     
     
       5. The method of  claim 4  wherein said free radical initiator includes a heat-curing-initiator to produce free radicals by thermal decomposition to cure said sealant. 
     
     
       6. The method of  claim 5  wherein said heat-curing initiator is selected from the group consisting of a peroxide, a hydroperoxide, a perester, an azonitrile and combinations thereof. 
     
     
       7. The method of  claim 4  wherein said free radical initiator includes an anaerobic-curing initiator to produce free radicals upon the exclusion of oxygen to cure said sealant. 
     
     
       8. The method of  claim 7  wherein said anaerobic-curing initiator is a peroxy initiator selected from the group consisting of hydroperoxides, peroxides, peresters and combinations thereof. 
     
     
       9. The method of  claim 7  wherein said anaerobic-curing initiator includes an anaerobic accelerator selected from the group consisting of tributyl amine, benzoic sulfimide, formamide, copper octanoate and combinations thereof. 
     
     
       10. The method of  claim 1  wherein said selecting said sealant further comprises selecting a curable poly(meth)acrylate ester having the formula: 
                 
 
       wherein R 1  represents a radical selected from the group consisting of hydrogen, lower alkyl of from 1 to about 4 carbon atoms, hydroxyalkyl of from 1 to about 4 carbon atoms and 
                 
 
       R 2  is a radical selected from the group consisting of hydrogen, halogen, and lower alkyl of from 1 to about 4 carbon atoms; R 3  is a radical selected from the group consisting of hydrogen, hydroxyl and 
                 
 
       m is 0 to about 12, n is equal to at least 1, k is 1 to about 4 and p is 0 or 1. 
     
     
       11. The method of  claim 10  wherein said selecting said sealant further comprises selecting a monofuctional acrylate ester, said monofunctional acrylate ester being selected from the group consisting of lauryl methacrylate, cyclohexylmetharylate, tetrahydrofurfuryl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, t-butylaminoethyl methacrylate, cyanoethylacrylate, chloroethylmethacrylate and combinations thereof. 
     
     
       12. The method of  claim 1  wherein said flexible graphite sheet is fluid-flow plate of a fuel cell. 
     
     
       13. The method of  claim 12  further including the step of providing a continuous fluid-flow channel in said fluid-flow plate. 
     
     
       14. A graphite sheet comprising:
 a. opposed planar outer surfaces defining an interior portion therebetween, said sheet being formed from exfoliated graphite particles to provide said interior with pores, said sheet having a plurality of holes extending from said interior of said sheet to at least one of said planar surfaces, wherein said holes are in fluid communication with said pores; and  
 b. a cured sealant filling said holes and said pores, such that said holes and said pores are filled substantially with said cured sealant to seal said graphite sheet.  
 
     
     
       15. The graphite sheet of  claim 14  wherein said cured sealant composition was formed from a curable sealant composition comprising a resin selected from the group consisting of a phenolic resin, a vinyl resin, a silicone resin, an acrylic resin, an epoxy resin, and combinations thereof. 
     
     
       16. The graphite sheet of  claim 15  further including a free radical initiator to initiate cure of said curable sealant composition. 
     
     
       17. The graphite sheet of  claim 16  wherein said free radical initiator includes a heat-curing initiator to produce free radicals by thermal decomposition to cure said curable sealant composition. 
     
     
       18. The graphite sheet of  claim 17  wherein said heat-curing initiator is selected from the group consisting of a peroxide, a hydroperoxide, a perester, an azonitrile and combinations thereof. 
     
     
       19. The graphite sheet of  claim 16  wherein said free radical initiator includes an anaerobic-curing initiator to produce free radicals upon the exclusion of oxygen to cure said curable sealant composition. 
     
     
       20. The graphite sheet of  claim 19  wherein said anaerobic-curing initiator is a peroxy initiator selected from the group consisting of hydroperoxides, peroxides, peresters and combinations thereof. 
     
     
       21. The graphite sheet of  claim 19  wherein said anaerobic-curing initiator includes an anaerobic accelerator selected from the group consisting of tributyl amine, benzoic sulfimide, formamide, copper octanoate and combinations thereof. 
     
     
       22. The graphite sheet of  claim 15  wherein said curable sealant composition further comprises a curable poly(meth)acrylate ester having the formula: 
                 
 
       wherein R 1  represents a radical selected from the group consisting of hydrogen, lower alkyl of from 1 to about 4 carbon atoms, hydroxyalkyl of from 1 to about 4 carbon atoms and 
                 
 
       R 2  is a radical selected from the group consisting of hydrogen, halogen, and lower alkyl of from 1 to about 4 carbon atoms; R 3  is a radical selected from the group consisting of hydrogen, hydroxyl and 
                 
 
       m is 0 to about 12, n is equal to at least 1, k is 1 to about 4 and p is 0 or 1. 
     
     
       23. The graphite sheet of  claim 22  wherein said curable sealant composition further comprises a monofunctional acrylate ester, said monofunctional acrylate ester being selected from the group consisting of lauryl methacrylate, cyclohexylmethacrylate, tetrahydrofurfuryl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, t-butylaminoethyl methacrylate, cyanoethylacrylate, chloroethylmethacrylate and combinations thereof. 
     
     
       24. The graphite sheet of  claim 14  wherein said flexible graphite sheet is fluid-flow plate of a fuel cell. 
     
     
       25. The graphite sheet of  claim 24  wherein said fluid-flow plate includes a continuous fluid-flow channel extending through said one planar surface.